1. Field of the Invention
The present invention relates to a display device and, more particularly, to a stacked structure (Printed Circuit Board) of a display device capable of preventing conductive noise due to signal interference by isolating analog and digital output stages and a ground stage onto different layers.
2. Description of the Related Art
Currently, various flat display devices having reduced weight and volume are being developed that overcome weight and volume disadvantages common to cathode ray tubes. These flat display devices include liquid crystal displays, field emission displays, plasma display panels, organic light emitting displays, and the like. Of these, an example of an organic light emitting display is shown in FIG. 1.
FIG. 1 is a plan view illustrating a general organic light emitting display.
Referring to FIG. 1, the display device includes a display panel 30 for displaying a predetermined image, a controller 10 for applying a driving control signal and a data signal to the display panel 30, and a connector 20 for connecting the controller 10 to the display panel 30.
Here, the controller 10 includes a control unit 12 and a DC-DC converter 13. The controller applies data signals and a power supply to each pixel along with the driving control signal to the display panel 30 via the connector 20. The display panel 30 causes a plurality of unit pixels to emit light in response to the driving control signals and the data signals from the controller 10.
Further, the controller 10 has an output stage 14 at one side thereof to which a first connection stage 21 of the connector 20 is connected. Further, the display panel 30 has an input stage 31 at one side thereof to which a second connection stage 22 of the connector 20 is connected. Accordingly, the data signals and power supply outputted from the controller 10 are applied to the output stage 14 via a printed circuit of the printed circuit board (PCB) 11 and are transmitted to the display panel 30 via the connector 20. Here, in one embodiment the connector 20 preferably is a PCB or flexible printed circuit board (FPCB).
FIG. 2 schematically shows a sectional and conceptual view of a stacked structure of a conventional display device.
As shown, in the conventional display device, first and second mounting layers 11a and 11b are formed at the front and rear of the conventional display device. Also thereon components such as the control unit 12, the DC-DC converter 13 and the like are mounted, and an output layer 11b connected with the components of the controller 10 through a via hole (not shown), and a ground layer 11c for grounding signals in the components are formed.
The output layer 11b includes a signal line for transmitting the control signal outputted from the control unit 12, and a power supply line for transmitting the power supply voltage outputted from the DC-DC converter 13. The digital signal and the analog signal outputted from the control unit 12 and the power supply voltage outputted from the DC-DC converter 13 are transmitted via the output layer 11b. 
Further, the connector 20 is generally formed from the PCB or FPCB as described above, and is composed of only the output layer 11b and the ground layer 11c, having no first and second mounting layers 11a and 11d in the mounting area of the controller 10 described above.
A problem with the stacked structure of such a conventional display device is that because the signal line and the power supply line are not isolated, or the digital signal and the analog signal are transmitted on the same layer, conductive noise due to signal interference is caused.